DISPARITY BETWEEN SEROLOGICAL REACTIVITY TO BORRELIA-BURGDORFERI AND EVIDENCE OF PAST DISEASE IN A HIGH-RISK GROUP

A prevalence study of past Lyme borreliosis in persons with outdoor oc cupations was done. Consenting individuals (n = 302) were administered a questionnaire eliciting demographic and occupational data and a cli nical history, and were asked to donate a serum specimen for detection of antibodies to Borrelia burgdorferi by enzyme-linked immunosorbent assay (ELISA), immunoblotting, and borrelia inhibition assays, and for detection of potentially cross-reactive antibodies. Of 302 individual s, 77 (25%) had reactive antibodies detected by ELISA. Of these 302 in dividuals, 44 (15%) met the criteria of the Centers for Disease Contro l and Prevention for serological reactivity as evidenced by immunoblot ting, and 70 (23%) had inhibitory activity. Through the clinical crite ria employed, only 11 individuals with serological reactivity had prio r illness compatible with Lyme borreliosis. Higher ELISA absorbances w ere positively correlated with age and duration of outdoor occupation. The results from three serological assays and the lack of reactivity to potentially crossreactive infectious agents indicate that serologic al reactivity was due to exposure to B. burgdorferi. The disparity bet ween serological reactivity and the clinical evidence of Lyme borrelio sis suggests cumulative exposure to a nonpathogenic form of B. burgdor feri.